Bicycle fork

ABSTRACT

A fork is provided for driving a driving wheel and especially the front wheel of a bicycle. Therefore the steerer is fixed to the axle of a wheel and extends at least partially to the rotation plane of the wheel in a parallel direction. Furthermore the steerer is designed generally as a frame square wherein at least two frame legs are arranged generally parallel and with a certain distance. The frame legs are fixed in a certain position by at least two connecting elements and are designed as profiled sticks. In a preferred embodiment of the contour of the profiled sticks has the shape of an aerofoil.

DESCRIPTION

[0001] The invention is related to a bicycle fork for guiding a wheel.

[0002] Bicycle forks are known from the state of the art and in ageneral embodiment comprise a control tube, a fork head and two forktubes.

[0003] A device is arranged at the lower end of the fork tubes whichallows the reception of the wheel axle. To correspond to thepredetermined mechanical characteristics, these fork tubes are builtfrom metal or light metal alloys.

[0004] The cylindrical head tube is guided by a steering tube providedin the frame and supported rotationally at both ends of the steeringtube by means of two ball races.

[0005] Besides of the mechanical characteristics for use in professionalbicycle sports, it is especially necessary to also adapt the region ofthe bicycle forks to aerodynamical requirements, whereby thereforestructures are used which have a reduced flow resistance.

[0006] It is the object of the present invention to provide a bicyclefork which has good mechanical strength characteristics and a low flowresistance.

[0007] The invention accomplishes this object by providing a fork forguiding a vehicle wheel according to the features of claim 1. Furtherpreferred embodiments of a bicycle fork for guiding a wheel are providedin the subclaims.

[0008] The fork for guiding a vehicle wheel according to claim 1comprises at least one fork brace which acts on a axle of the wheel andextends at least partially in one direction which is substantiallyparallel to the rotational axis of the guided wheel.

[0009] The fork brace is formed substantially as frame quadranglewherein the frame quadrangle consists of at least two frame legsarranged substantially parallel and of connection elements which arespaced with respect to each other.

[0010] The frame legs are held in at least two regions by the connectionelements in their relative position to each other wherein according toone preferred embodiment of the invention also further connectionelements may be provided.

[0011] The frame legs themselves are realised at least partially asprofile ledges.

[0012] By the determined arrangement of the frame legs and theconnection regions, a flow channel is defined between the profile ledgeswhich due to the arrangement of the frame legs extends substantiallyalong the flow direction of the air flowing around the fork brace.

[0013] In a specific embodiment, the aforementioned fork brace whichessentially is formed as a frame quadrangle is finished by connectionregions which on one side comprise the fork head and to the other sidethe reception device for a wheel axle.

[0014] The bicycle fork according to claim 1 in a further embodiment ischaracterised in that the fork brace is arranged in a predeterminedangle with respect to a vertical center axis.

[0015] Thereby, the fork brace has an angle between 45 degrees and 1degree, in an preferred embodiment an angle between 30 degrees and 5degrees, and in a very preferred embodiment an angle between 20 and 7degrees.

[0016] The fork for guiding a vehicle wheel in a very preferredembodiment comprises a connection means especially a head tube whichextends in extension to the stop element, especially to the fork headand which is guided by a steering tube provided in the frame andpivotally supported at both ends of the steering tube by means of twoball races (control set).

[0017] In a further preferred special embodiment for guiding a rearwheel, the fork especially for a bicycle comprises a fixing device whichis connected with the bicycle frame. According to an especiallypreferred embodiments, the fork may comprise further braces to keep therear wheel in a predetermined position.

[0018] According to a further embodiment of the present invention, theframe legs used for forming a fork brace are provided as profile ledgeswhich are defined by a profile contour. Said profile contour may bedefined at least by the profile depth and the profile thickness at atleast one point of the profile depth.

[0019] The connection line of two maximally spaced profile contourpoints is also called chord, whereby additionally for characterising theprofile contour also a so-called skeleton line is used which follows asaxis of the so-called thickness distribution over the profile depth.

[0020] The profile depth according to the present invention isunderstood as a measure for the maximum distance of two contour pointsand extends substantially along the flow direction of the air flowingaround the profile.

[0021] The profile thickness of the profile contour depends on theprofile depth wherein at least at one point the distance of two profilecontour points is described whose connection line is perpendicular tothe chord. The profile contour follows as generating curve of anenvelope of the profile contour points wherein an increasing number ofprofile contour points lead to a more precise definition of the profilecontour.

[0022] According to a specific embodiment of the present invention, theprofile contour of the used profile ledges is selected such thatespecially the flow resistance with respect to the air flowing aroundand/or flowing through is low and simultaneously, the profile ledges arearranged with respect to each other in such a way that the air flow isdirected in a predetermined direction. Especially the profile ledges arearranged such that the air flow is directed away from the wheel arrangedbetween the fork braces.

[0023] In a preferred embodiment, the profile ledges are arranged insuch a way that the flow courses of the air at the surface regions ofthe single profile ledges are directed such that the flow courses of theair of the profile ledges arranged essentially parallel to each other donot influence each other negatively. According to the present inventionit is intended especially to possibly connect turbulent flow regions orto reduce them.

[0024] According to a further preferred embodiment, the fork for guidingthe wheel is characterised in that the fork braces, especially the framelegs or the connection regions consist of at least one material or acombination of materials and the material or the materials are selectedfrom a group of materials which contains metals, as e.g. aluminum,titan, synthetic materials, natural materials, fibre glass, carbon,kevlar, fibre glass, composite materials, fibre glass compositematerials, polyester, epoxy resin, polymers, natural materials as e.g.wood, latex or the like.

[0025] Besides of the use of the aforementioned materials or materialcombinations, the bicycle fork for guiding a bicycle is characterised inthat in a especially preferred embodiment the profile ledges of the forkbraces are manufactured from structure elements which especiallycomprise the form of honeycomb structures or correspondingmicrostructures.

[0026] According to a further preferred embodiment, the fork for guidinga wheel is characterised in that the profile ledges, fork braces and/orthe connection elements are connected with each other by plugconnections, bolted connections, adhesive joints, welded joints,soldered joints or similar joining methods and the connection regionsare shaped such that the flow resistance is minimised.

[0027] In a further preferred embodiment, the connection elementsbetween the profile ledges are characterised in that they extendsubstantially between the surfaces of the profile ledges and that theyare shaped such that the flow resistance for the air flowing around isminimised.

[0028] In a very preferred embodiment, the connection elements are madeof one piece.

[0029] According to a very preferred embodiment, the fork for guiding awheel is characterised in that the profile ledges and the connectionregions are arranged such that predetermined requirements on themechanical properties of the fork brace are achieved.

[0030] These mechanical properties are especially the flexural stiffnessand flexural strength, torsional stiffness and torsional strength,flexibility, strain, pressure resistance and breaking strength of thefork brace, of the connection elements and the bicycle fork.Furthermore, the mechanical properties are also achieved by theconnection regions, respectively connection methods. It is mentioned,however, that this enumeration does not finally characterise themechanical properties of the fork brace, but that further referencevalues of the material necessary for the use of the fork brace areobtained by the shaping of the profile ledges and their arrangement.

[0031] With respect to the shape of the profiles, according to a furtherpreferred embodiment, the profile contour is selected such that the flowpath of the air particularly the length of the flow path on the upperside of a profile differs from the lower side of the profile. A furtherembodiment provides that the profile contour of the profile ledgesarranged substantially parallel to each other, differ.

[0032] In a further preferred embodiment, the surface structure of thewhole bicycle brace is selected such that the flow resistance of thebike fork is minimised. This can be achieved among others by forming thesurface of the fork brace such that vortexes occurring on the surfaceare damped by the surface structure. In a very preferred embodiment,this is achieved by use of a so-called shark-fin structure, groovedstructure or notched structure.

[0033] A further embodiment of the bicycle fork for guiding a wheel ischaracterised in that the fork brace is formed substantially as a framequadrangle and in that the frame legs and connection regions areconnected one piece to each other.

[0034] In the following, the invention is detailed explained in theembodiment with the following drawings:

[0035] Herein show:

[0036]FIG. 1 a front view of a bicycle fork for guiding a wheelaccording to one embodiment of the present invention;

[0037]FIG. 2 a perspective side view of a bicycle fork according to anembodiment of the present invention;

[0038]FIG. 3 a perspective sectional view of a fork brace in the regionof a middle connection segment;

[0039]FIG. 4 a schematic view of a profile contour with scale;

[0040]FIG. 5 a schematic view of a first profile contour;

[0041]FIG. 6 a schematic view of a second profile contour;

[0042]FIG. 7 a schematic sectional view of a connection region alongline A from FIG. 2;

[0043]FIG. 8 a schematic cross sectional view of a bicycle fork fromFIG. 1.

[0044] The figures show an embodiment for a fork for guiding a vehiclewheel especially for the front wheel of a bicycle which comprises atleast a fork brace which acts on an axle of the wheel and at leastpartially extends in a direction substantially parallel to therotational axis of the wheel.

[0045] The figures especially describe a bicycle fork for a front wheel,however, it is pointed out that the bicycle fork also may be used for arear wheel, especially for a bicycle.

[0046]FIG. 1 shows a fork for guiding a wheel according to an embodimentof the present invention which comprises of the fork tube 1 as well as afork head 2 and the fork braces 3 a and 3 b.

[0047] The fork braces 3 a and 3 b are formed substantially as framequadrangles and besides of the frame legs 4 and 5 comprise theconnection elements 6 a, 6 b and 6 c. By the arrangement of the framelegs 4 and 5 and the connection regions, the fork brace comprises theflow channels 9 a and 9 b which extend along a main extension directionof the fork brace and at least during operation are passed by air. Inextension to the connection element 6 b, the fork brace comprises afinal region 8 which comprises means for the reception of the bicycleaxle (not shown).

[0048] The connection region 6 c finishes the fork brace 3 b to theupper side and is connected with the fork head 2 via the transitionregion 7.

[0049] The fork braces 3 a and 3 b are arranged at a predetermined angleα, respectively α′, with respect to a vertical center axis. According tothe present invention, the predetermined angle α, respectively α′, isbetween 2° and 30°, preferably between 20° and 3° and most preferablybetween 15° and 5°.

[0050]FIG. 2 shows a perspective view of a bicycle fork according to anembodiment of the present invention, wherein the bicycle fork, apartfrom the fork tube 21, the fork head 22, the transition region of thefork head to the fork brace 27, comprises the frame legs 24 and 25 andthe transition regions 26 a, 26 b and 26 c. The region 28 serves as endof the fork brace and provides a means for reception of the bicycle axle(not shown).

[0051] According to the present invention, the bicycle fork is arrangedsuch that the air flow L hits the bicycle fork from the right sidecorresponding to the figure and flows around, respectively through thebicycle fork.

[0052]FIG. 3 shows a mean perspective sectional view of a fork brace inthe region of a middle connection element from FIG. 2.

[0053] Beside the connection element 36, the two profile ledges 34 and35 are shown. Between the profiles, as an extension to the connectionregion 36, the flow channels 39 a and 39 b are provided through whichair flows during operation of the bicycle. The arrow L in FIG. 3indicates the flow direction of the air occurring in regular operation.

[0054]FIG. 4 shows a schematic view of a profile contour with scales,wherein the profile depth x as well as the profile thickness y_(m)at theposition x_(n) of the profile depth is shown. The profile contour 40follows from the generating curve of an envelope connecting the profilecontour points.

[0055]FIG. 5 is a preferred embodiment of a profile contour for a frameleg, whose profile depth x₁ is especially between 100 mm and 20 mm,preferably between 70 mm and 20 mm and most preferably between 25 mm and50 mm.

[0056] The profile thickness y₁ of the frame leg is especially between20 mm and 2 mm, preferably between 15 mm and 3 mm and most preferablybetween 10 mm and 5 mm.

[0057] In a view according to FIG. 5, the profile contour 50 isindicated by a front region 51 which to the left end of the profile viewcomprises a transition point 53 which ends in the region 52 of theprofile contour.

[0058]FIG. 6 shows a second profile contour of a frame leg according tothe present invention, whose profile depth x₂ is between 100 mm and 10mm, preferably between 70 mm and 15 mm, and most preferably between 50mm and 25 mm.

[0059] The profile thickness y₂ of such a profile according to theinvention is between 20 mm and 1 mm, preferably between 15 mm and 3 mm,and most preferably between 10 mm and 5 mm.

[0060]FIG. 7 shows a sectional view of a fork brace 23 along the line Afrom FIG. 2. The connection element 26 a and the frame legs 24 and 25are shown in a sectional view. The two chords 71 and 72 of the framelegs 24 and 25 intersect each other in a point A and, according to thepresent invention, form an angle between 0.5° and 10°, preferablybetween 0.7° and 7° and most preferably between 1° and 5°.

[0061] The distance a between the two front edges of the frame legs 24and 25, according to the present invention is between 5 mm and 50 mm,preferably between 10 mm and 40 mm and most preferably between 5 mm and35 mm.

[0062] The generating curve of an envelope 70 according to the presentinvention comprises a profile depth between 100 mm and 20 mm, preferablybetween 80 mm and 35 mm and most preferably between 65 mm and 40 mm.

[0063] The profile thickness of the generating curve of an envelope 70according to the present invention is between 5 mm and 50 mm, preferablybetween 10 mm and 35 mm and very preferably between 15 mm and 25 mm.

[0064] According to the present invention, the preferred flow directionof the air is indicated by the arrow L. According to the figure, the airflow during operation hits from the right side on the fork brace andflows around the same along the frame legs 24 and 25.

[0065]FIG. 8 shows a further sectional view of the fork braces 3 a and 3b. Apart from the generating curves of an envelope 80 and 80′, thefigure shows the two frame legs 25 and 24, and 25′ and 24′. The “airstream” of the frame legs substantially takes place along the arrowdirection L, wherein the air passes according to the arrows L2 along thesurfaces of the generating curves of an envelope 80 and 80′ in theregion of the connection elements and along the surfaces 24 and 25, and24′ and 25′, between the connection elements.

[0066] The air flow running between two frame legs is guided away from awheel, especially a wheel rim which is arranged between the two forkbraces on the center plane M.

1. Fork for guiding a vehicle wheel, particularly the front wheel of abicycle, comprising at least one fork brace (3 a, 3 b) for engaging anaxle of the wheel, the fork brace extending at least partially in adirection substantially parallel to the rotational plane of the wheel,wherein the fork brace (3 a, 3 b) is substantially formed as a framequadrangle, wherein the quadrangle comprises at least two frame legs(4,5) arranged substantially parallel to each other and spaced apartfrom each other (4, 5), and wherein the frame legs are held by at leasttwo connection elements (6 a, 6 b, 6 c) at their position with respectto each other.
 2. Fork according to claim 1, wherein the frame legs (4,5) are at least partially formed as profile ledges.
 3. Fork according toclaim 1, wherein the fork braces (3 a, 3 b) are connected with eachother by at least one fixing means (2), particularly by a fork head. 4.Fork according to claim 3, wherein the fixing means (2) comprisesconnection means (1), particularly a fork tube, by means of which thefork is connectable to a bicycle frame.
 5. Fork according to claim 1,wherein each fork brace (3 a, 3 b) is arranged at a predetermined anglewith respect to a vertical middle axis and said angle is between 45° and1°, preferably between 30° and 5° and most preferably between 20° and7°.
 6. Fork according to claim 2, wherein the profile ledges arecharacterised by a profile contour and this profile contour is formed asan airfoil.
 7. Fork according to claim 2, wherein the shape and thearrangement of the profile ledges (4, 5) is selected such that the airflowing around and/or through the frame quadrangle is guided to apredetermined direction, especially away from the longitudinal centerplane M of the wheel.
 8. Fork according to claim 7, wherein thearrangement of the profile ledges (4, 5) is selected such that the flowresistance is minimised.
 9. Fork according to claim 4, wherein the forkbraces (3 a, 3 b), the fixing means, the connection element and theconnection means are made of a material selected from a group consistingof metals, synthetic material, natural materials, fibre glass, carbon,kevlar, glass fibre, compound materials, polyester, epoxy resins,polymers, wood, latex, aluminium and titan.
 10. Fork according to claim2, wherein the profile ledges (4, 5) of the fork braces (3 a, 3 b)and/or the connection elements (6 a, 6 b, 6 c) comprise structuredelements, especially honeycomb structures or microstructures.
 11. Forkaccording to claim 2, wherein the profile ledges (4, 5), the connectionelements (6 a, 6 b, 6 c) and/or fork braces (3 a, 3 b) are connected bya type of connection selected from the group consisting of plugconnections, bolt connections, adhesive connections, welded connections,and soldered connections.
 12. Fork according to claim 2, wherein theprofile ledges (4, 5) and the arrangement of the profile ledges areselected such that the mechanical properties of the fork brace (3 a, 3b) are adapted to meet predetermined requirements.
 13. Fork according toclaim 12, wherein the mechanical properties are selected from a group ofproperties consisting of the flexural stiffness and strength, torsionalstiffness and strength, flexibility, strain, pressure resistance andbreaking strength.